In order to write data to and read data from a media, a recording head is typically used. FIGS. 1 and 2 depict side and perspective views of portion of a conventional perpendicular magnetic recording (PMR) head 10. For simplicity, only the write transducer 20 is shown in FIGS. 1 and 2. In addition, for clarity, FIGS. 1 and 2 are not drawn to scale. Although only the write transducer 20 is shown, the conventional write transducer 20 is generally part of a merged head that includes the transducer for writing, a read transducer for reading data from the media, and a slider. In addition, for clarity, only the conventional second pole (P2) 30 and the PMR write pole 32 are depicted in FIG. 2.
The conventional PMR head 10 includes a conventional first pole (P1) 22, insulator 24, a first coil 26, P1 pad 28, the conventional P2 30, the conventional PMR write pole (or main pole) 32, insulator 24, write gap 36, a shield pad 34, a second coil 38, and shield 40. The conventional P2 30 has a length perpendicular to the ABS that is on the order of thirteen to sixteen micrometers. Although not explicitly shown, seed layer(s) may be used in providing the conventional poles 22, 30, and 32. The conventional PMR write transducer 20 is also depicted with two coils 26 and 38. However, PMR heads having a single coil are also typically used.
In order to write data to a PMR media, the coils 26 and 38 are energized. Consequently, the conventional P2 and 30 conventional PMR pole 32 are magnetized and the media written by flux from the pole tip of the conventional PMR pole 32. Based on the direction of current through the coils 26 and 38, the direction of magnetic flux through the conventional PMR pole 32 changes. Thus, bits having opposing magnetization can be written and the desired data stored on the PMR media.
Although the conventional PMR head 10 functions, there are drawbacks. The conventional PMR head 10 may suffer from a low field rise time. A low field rise time may result, at least in part, from the inductance of the conventional head 10. This large inductance increases the time for the current through the coils 26 and 38 to change as well as the time for the corresponding magnetic field to be generated by the poles 22, 30, and 32. Consequently, write speed may be adversely affected. As a result, the conventional PMR head 10 may be unsuitable for use at higher data rates.
The conventional PMR head 10 may also be subject write pole tip protrusion, which adversely affects disk drive reliability. During use, a write current is driven through the coils 26 and 38. Write currents in the coils 26 and 38, and other currents such as eddy currents in the core of the conventional write transducer 20, may heat the conventional write transducer 20. The relatively large resistance of the coil(s) 26 and 38 may exacerbate this heating, particularly in the region of the conventional PMR pole 32 and conventional P2 30. The conventional P1 22, conventional P2 30, conventional PMR pole 32, and conventional shield 40 typically have large positive coefficients of thermal expansion in comparison to the insulator 24 and write gap 36. When heated, therefore, the tips of P1 22, the conventional PMR pole 32, and the shield 40 near the ABS expand, protruding outward toward the ABS. The protrusion of these components 22, 32, and 40 is known as pole tip protrusion. This pole tip protrusion adversely impacts the reliability of disk drives using the conventional PMR head 10 because a protruding pole is more likely to contact the media during operation.
In addition, the conventional P2 30 has may have domains (not explicitly shown) that are not aligned parallel to the ABS. Instead, the P2 30 may have a complicated domain structure, with domains aligned in a variety of directions. Thus, the domains in the conventional P2 30 may be more difficult to align in the desired direction for recording. Consequently, performance of the conventional PMR head 10 may be adversely affected, particularly at high data rates.
Accordingly, what is needed is a system and method for improving the performance and reliability of the conventional PMR head 10, particularly at higher data rates.